I own a 10 gallon tank with lots of hiding places and plants. Inside are 6 black skirt tetras, 3 or 4 -small- ghost shrimp, and one veil tail betta (Gemma or Gem) . I've had this community for quite a bit now and everyone was getting along quite nicely. Then today, one of the tetras went after Gems fin, and all hell broke loose. Gem started flaring so hard he um, pooped, and then started darting at all the Tetras and chasing them. Help?!?

Black skirts are unfortunately one of the more aggressive of the tetras for small communities, Black Phantoms are a little more playful. But I'd say you've got a fight on your hands. I would take Gem out immediately before anything gets worse, if he's got any tears or anything keep him in the hospital tank with a double dose of Stress Coat if you have it and then get him his own tank or (sorry to say this) get rid of the Black Skirts who are known to be fin nippers.

Sometimes things can be super peaceful but then one will just snap and as you said, hell will break loose. It would be safer for everyone if they were separated.